harris



Dec. 24, 1935. Y J. MCA, HARRls, JR 2,025,387

PROCESS OF TREATING LUBRICATING OILS Filed Aug. 4, 1933 OX ADIZ ING TANK MIXING T'A/VK C'IV/LLER.

SUPEZHEA TED STEAM .SOLVENT LINE/ 1 .SETTL ER l Z5 Z2 SOLVE/V7 TANK E I j v 24 F L 11 24 25 1g 16 "lg etroletun,

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ound that the lubricating fractions 10111 petroleum frequently contain con-- stitueis which cause the oil to haze r become cloudy at-temperatures above the pour point. This is particularly true of hydrogenated oils which 10 are prepared by subjecting petroleum fractions to the action of free hydrogen at high temperatures and pressures, These constituents moreover do not appear to be removed from the oil by the ordinary methods of dewaxing.

One object of the present invention is to provide a method by which haze forming constitu-= ents present inlubricating ofls may be removed by the dewaxing treatment. The method consists in subjecting the oil to be dewaxed to a prelim- 20 inary treatment with oxygen or oxygen containing gases. This preliminary treatment is found to convert the haze forming constituents into a form in which they are substantially completely eliminated by the usual methods of dewaxing.

Another object of the present invention is to provide a method by which those constituents of an oil which tend to form sludge when the oil is used in internal combustion engines may be removed by the usual methods of finishing the oil.

The invention will be fully understood from the following description read with reference to the accompanying drawing which is a semi-diagrammatic View in sectional elevation of the type of apparatus suitable for the purpose:

Referring to the drawing numeral i designates a pump which withdraws oil to be treated from a suitable storage tank (not shown) and forces it through line 2 into tank (-3 provided with a heating means t and a pressure release means 40 5. Pump b forces air or other oxygen-containing gas through line i? into tank 3 wherein the oil is subjected to the action of the oxidizing gas. The temperature is maintained at a suitable point by means of the heating coil is which may be provided. with superheated steam or other heating medium.

'"ter the oil has been subjected to the action of the oxidizing gas for a suflicient length of time, it is withdrawn from tank 3 through line 8 and introduced into a mixing tank 9 provided with a stirring means A suitable dewaxing solvent is withdrawn from a storage tank it by means of pump it. and forced through line intotanlrb wherein it is thoroughl d with the oil. The mixture oi oil and sclven s withdrawn of pump it and forced through line Ell into a s distillation means 2E wherein the solvent is distilled oil from the oil. The vapors of solvent pass through line 22 into a condensing means 23 and thence the condensate is returned to the solvent storage tank 5 l by means of valved line 24!. The dewaxed oil is withdrawn from the still by means of pump 25 and forced through line 2% .to means for additional treatment or storage (not shown The gas used to oxidize the oil may be an}, oxygen-containing gas such as air. The temper ature maintained in the oxidizing tank should be above about 150 F. and preferably between 300 and 500 F. The pressure maintained may either be atmospheric or above. Catalysts which promote the oxidation are advantageously used. As examples of such catalysts may bementioned finely divided charcoal or manganese stearate.

It will be understood that the primary pur pose of the oxidizing treatment is to convert haze-- forming and/or sludge forming constituents into a form in which they are readily removable by the usual methods of dewaxing. Thus the extent to which the oxidation is allowed to proceed is preferably strictly limited so that the yield of oil is not substantially diminished by the formation of oxidation products. In most cases the X- idizing reaction should be controlled so that not more than say 1 to of the oil is converted to oxidized products. In some cases, however, valuable oil oxidation products may be obtained so that it is desirable in these cases to allow oxidation to proceed until say to or more of the oil has been oxidized. The exact time to which any particular oil should be exposed to the oxidizing reaction. will naturally depend upon the nature and quantity of the haze-forming and sludge-forming constituents contained in it. In general, however, the length of time to which the oil is exposed to oxidizing conditions is suiiicient only tcconvert the undesirable constituents into i a form in which they may be readily removed by the subsequent dewaxing treatment.

The dewaxing treatment ,may be carried out accord ng to ar y" the usual dewaxing methods great variety or" diiierent solvents may be used, such as naphtha, liquefied normally gaseous hydrocarbons, benzol, toluol, acetone, butyl acetate, tri-chlorethylene and the like.

The diluted oil is chilled to a temperature at which wax is caused to separate. This will generally be below 32 F. and is preferably below F. or lower.

The precipitated wax may be separated from the solution by any suitable means such as filtration, centrifuging or cold settling and the waxfree oil may be recovered from the solution by distilling ofi the diluent.

It is found that the dewaxed oil so obtained shows substantially no tendency to haze at relatively low temperatures.

It will be understood that this process is subject to various modifications. For example, they oxidation treatment may be carried out after the oil has been dewaxed instead of before. However, this involves a second chilling step in order to remove the haze-forming constituents so that the oxidation is generally more advantageously preliminary to the dewaxing step.

The oxidation and dewaxing steps themselves are also subject to wide variation and it should be understood that the present invention is not restricted to any particular methods of accom plishing either step.

This invention is not limited by any th of the mechanism of the reactions nor by details which may have been given merely illustrative purposes, but is limited only in and by the following claims in which I wish to claim all novelty inherent in the invention.

I claim:

1. The method of treating wax-contalning hydrocarbon oils having a tendency to haze on standing which comprises first subjecting such oil to oxidation at a temperature between 150 and 500 F. for a time only sufficient to oxidize about 1 to 5% of the oil and thereafter dewaxing the oil.

2. The method of treating hydrocarbon oils which tend to haze on standing which comprises subjecting the oil to the action of oxygen-containing gas at a temperature between 300 and 500 F. for a time insufficient to oxidize more than about 5% of the oil, then diluting the oil with several volumes of a suitable dewaxing solvent, chilling the mixture to a wax-separation temperature, and removing the precipitated material and solvent from the oil.

3. The method of treating a wax-containing hydrocarbon oil to produce a lubricating oil which is resist-ant to oxidation and has low haze-forming and sludge-forming tendencies, which comprises subjecting the hydrocarbon oil to the action of oxygen containing gases at a temperature between 150 and 500 F. for a time insuificient to oxidize more than about 5% of the oil, and

then dewaxing the oil. 

